WIKA Intelli Therm TGT73.100, Operating Instructions Manual

Page: 11 / 92

EN
14028755.03 02/2021 EN/DE/FR/ES
WIKA operating instructions model TGT73 11
4. Design and function
4.1 Description
The gas-actuated thermometer consists of a stem, capillary, Bourdon
tube and transmitter in the casing. These parts are combined to form a
single unit. The entire measuring system is filled with an inert gas under
pressure.
Any change in temperature causes a change in internal pressure in the
stem, and thus a change in the shape of the pressure element.
This motion is converted, via a mechanical movement, into a rotational
motion. A magnet on the pointer shaft rotates proportionally to the
instrument pointer as a direct linear function of the process temperature.
The downstream electronics detect the rotational motion of the magnet
in the display range.
A magnetic-field dependent rotational sensor picks up this change on
the electronics side, contact-free, wear-free and without reaction on the
pressure element.
The rotational motion is converted into an electrical signal. The
electronics are factory set to the standard 4 ... 20 mA passive or
0 ... 10 V output signal. The span of the electrical output signal
corresponds to the measuring span on the dial.
Through these two standard electrical output signals, this instrument
can be set to almost any range in the industry.
Thermometers from the intelliTHERM range with transmitters combine
all the advantages of a local mechanical display with the industry‘s
requirements for electrical signal transmission and a modern measured
value registration.
Variations in the ambient temperature acting on the case are
compensated for by a bimetal element mounted between the movement
and the Bourdon tube.
Scale ranges with accuracy class 1 per EN 13190
between -200 ... +700 °C
4. Design and function